Model-Based Controller for Paper Machine Drying Section
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The drying section of paper machines is energy-intensive and often a bottleneck in production, limiting throughput and increasing costs, with existing controllers failing to effectively model and optimize energy consumption across the entire drying process.
Innovation Solution
A model-based controller that distinguishes between material streams in the drying section, calculates mass and energy balances, and optimizes specific energy consumption by setting points for parameters like temperature, humidity, and steam pressure, using an online model to adapt and predict optimal operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional drying section operation is used, then the paper machine can maintain basic drying function, but energy consumption is high and throughput is limited
Solution Approach 1:
The patent applies preliminary action by performing what-if calculations and optimizing operating parameters before actual drying operations occur. The system pre-calculates optimal steam pressures, temperatures, and airflow rates based on stored process data and machine state, allowing the drying section to operate at peak efficiency from the start, thereby reducing energy consumption while maximizing throughput without needing to adjust conditions during operation.
Solution Approach 2:
The patent implements dynamics by continuously adapting drying parameters to changing machine conditions. The system dynamically adjusts steam pressures in different drying zones, modifies airflow rates, and changes temperature profiles based on real-time measurements of paper moisture content, machine speed, and environmental conditions, enabling optimal energy utilization across varying production rates and paper types.
2Loss of energy
If existing controllers are used, then basic control functions are provided, but they fail to effectively model and optimize energy consumption across the entire drying process
Solution Approach 1:
The patent applies segmentation by dividing the drying section into multiple independently controllable zones (e.g., pre-dryer, main dryer, after-dryer) with separate steam systems and control parameters. Each zone can be optimized individually based on local moisture requirements and energy conditions, allowing detailed energy management without requiring complete redesign of the entire control system architecture.
Solution Approach 2:
The patent implements feedback by continuously measuring actual drying results (paper moisture content, energy consumption) and comparing them with target values and predicted outcomes. The system uses this feedback to adjust operating parameters in real-time and for future what-if calculations, creating a closed-loop optimization that reduces energy losses while adapting to changing conditions without requiring overly complex control algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces specific energy consumption, increases throughput, and enhances production rate by optimizing energy use and plant availability, while also providing diagnostic insights and warning signals for improved maintenance and safety.
Implementation Method 1
a mass and energy balance for all the material streams is calculated in each case in the drying section
Implementation Method 2
a mass and energy balance for all the material streams is calculated in each case in the drying section
Implementation Method 3
exhaust heat recovery system
Implementation Method 4
drying section, possibly subdivided into pre-dryer section and after-dryer section
Implementation Method 5
drying section, possibly subdivided into pre-dryer section and after-dryer section
Implementation Method 6
steam and condensate system
Data Source
AI summary
In order to achieve an improved or optimized operation mode of an “expanded drying section” of a paper machine—having the “actual” drying section, separated, if applicable, into pre-drying and post-drying sections with a size press located therebetween, a steam and condensate system, an exhaust air heat recovery system, a wet press and the white water—a model that includes the above system components is proposed, with which mass and energy balances for the system components as well as the specific energy consumption of the drying section are calculated, based on values for parameters relevant for the drying process.